1. Field of the Invention
The present invention relates to respiratory interface devices for transporting a gas to and/or from an airway of a user, and in particular, to respiratory interface devices, such as masks, that include a fabric body constructed of a fabric material.
2. Description of the Related Art
A variety of respiratory masks are known which contact the areas surrounding the nose and/or mouth of a human user and that are designed to create an effective fit against the user's face. Typically, gases can be provided at a positive pressure within the mask for consumption by the user. The uses for such masks include high altitude breathing (aviation applications), swimming, mining, fire fighting and various medical diagnostic and therapeutic applications.
One requisite of many of these masks, (e.g.) particularly medical respiratory masks, is that they provide an effective fit against the user's face and that the mask contours with the user's face to limit or prevent leakage of the gas being supplied. Commonly, in conventional mask configurations, an effective mask-to-face fit has been attained in many instances only with considerable discomfort for the user. This problem is most crucial in those applications, especially medical applications, which require the user to wear the mask continuously for hours or perhaps even days. In such situations, the user often will not tolerate the mask for long durations and therefore optimum therapeutic or diagnostic objectives will not be achieved, or will be achieved with great difficulty and considerable user discomfort.
Several types of respiratory masks for the types of applications mentioned above are known. Perhaps the most common type of mask incorporates a substantially rigid structure such as a faceplate to support the more flexible sealing member which comes into contact with the user's face, such as a back cushion portion. The rigid structure of the faceplate restricts or limits the ability of the cushion portion to conform to the facial contours of the user. If the fit is not effective, there will be gaps in the mask-to-face interface resulting in gas leaking from the mask at the gaps.
Considerable force will be required to compress the mask member to close the gaps and attain a satisfactory seal in those areas where the gaps occur. Typically, this required force will be provided by straps that are connected to the mask to securely fit the mask to the face of the user. Such force is undesirable because it produces high pressure points elsewhere on the face of the user where the mask contour is forcibly deformed against the face to conform to the user's facial contours. This will produce considerable user discomfort and possible skin irritation and breakdown anywhere the applied force exceeds the local perfusion pressure, which is the pressure that is sufficient to cut off surface blood flow. Thus, it would be desirable to minimize or eliminate the rigid structure of the mask to improve the ability of the cushion portion to conform to the facial contours of the user and therefore to enhance the fit of the mask to the user's face.